The cardiovascular system, including the coronary circulation, is regulated to a large extent by the neural reflexes. One of the lesser known reflexogenic areas, the visceral organs, including the stomach and gall bladder, have been demonstrated to exert significant changes in blood pressure, heart rate and myocardial contractility when stimulated pharmacologically with capsaicin. The proposed work seeks to investigate the physiological mechanisms which induce these visceral-cardiovascular reflexes as well as the neurophysiologic characteristics of the afferent pathways involved in their transmission. The effects on heart rate, blood pressure, myocardial contractility and regional blood flow of organ distension and gastric stimulation by local intraarterial injection of bradykinin, prostaglandins, and acetylcholine will be determined. Subsequently, during receptor stimulation with capsaicin or by one of the above mentioned physiologic mechanisms, the afferent pathways will be characterized by afferent nerve recordings to define their fiber size, discharge characteristics and relation to both receptor and cardiovascular response. This study will allow further characterization of the mechanisms of visceral receptor stimulation in the stomach and gall bladder. Reflexes from the splanchnic area may be important since they may contribute a significant degree of control of the cardiovascular system during both normal physiologic states and abnormal states, including post prandial angina pectoris.